Spontaneous negative pressure changes: an unusual cause of noncardiogenic pulmonary edema.

The principal physiologic mechanism underlying the formation of negative pressure pulmonary edema (NPPE) is thought to be the creation of excessive negative intrathoracic force from inspiration against a critical obstruction of the upper airway. The increased subatmospheric transpulmonary pressures result in transudation of fluid from the pulmonary capillaries to the interstitium and alveoli. The clinical picture is that of pulmonary edema. Aggressive diagnostic and therapeutic intervention can be avoided if the syndrome is recognized early. This report highlights the clinical features of NPPE and serves as a reminder to the clinician that although NPPE can cause significant morbidity, conservative supportive therapy typically results in a good outcome.